Package org.apache.commons.io.build

Class AbstractSupplier<T,B extends AbstractSupplier<T,B>>

java.lang.Object
org.apache.commons.io.build.AbstractSupplier<T,B>
Type Parameters:
T - the type of instances to build.
B - the type of builder subclass.
All Implemented Interfaces:
IOSupplier<T>
Direct Known Subclasses:
AbstractOrigin, AbstractOriginSupplier, WildcardFileFilter.Builder
public abstract class AbstractSupplier<T,B extends AbstractSupplier<T,B>> extends Object implements IOSupplier<T>
Abstracts supplying an instance of T.

Extend this class to implement the builder pattern.

For example, here is a builder, a domain class, and a test.

The builder: 

    /**
     * Builds Foo instances.
     */
    public static class Builder extends AbstractSupplier<Foo, Builder> {

        private String bar1;
        private String bar2;
        private String bar3;

        /**
         * Builds a new Foo.
         */
        @Override
        public Foo get() {
            return new Foo(bar1, bar2, bar3);
        }

        public Builder setBar1(final String bar1) {
            this.bar1 = bar1;
            return this;
        }

        public Builder setBar2(final String bar2) {
            this.bar2 = bar2;
            return this;
        }

        public Builder setBar3(final String bar3) {
            this.bar3 = bar3;
            return this;
        }
    }

The domain class: 

    /**
     * Domain class.
     */
    public class Foo {

        public static Builder builder() {
            return new Builder();
        }

        private final String bar1;
        private final String bar2;
        private final String bar3;

        private Foo(final String bar1, final String bar2, final String bar3) {
            this.bar1 = bar1;
            this.bar2 = bar2;
            this.bar3 = bar3;
        }

        public String getBar1() {
            return bar1;
        }

        public String getBar2() {
            return bar2;
        }

        public String getBar3() {
            return bar3;
        }

    }

The test: 

    @Test
    public void test() {
        final Foo foo = Foo.builder()
            .setBar1("value1")
            .setBar2("value2")
            .setBar3("value3")
            .get();
        assertEquals("value1", foo.getBar1());
        assertEquals("value2", foo.getBar2());
        assertEquals("value3", foo.getBar3());
    }
Since:
2.12.0

  • Constructor Details

  • Method Details

    • asThis

      protected B asThis()
      Returns this instance typed as the subclass type B.

      This is the same as the expression: 

       (B) this
      Returns:
      this instance typed as the subclass type B.